Evolved Packet System (EPS) is the evolved 3rd Generation Partnership Project (3GPP) Packet Switched Domain. EPS includes Evolved Packet Core (EPC), and Evolved Universal Terrestrial Radio Access Network (E-UTRAN). FIG. 1 shows an overview of the EPC architecture in a non-roaming context, which architecture includes a Packet Data Network (PDN) Gateway (PGW), a Serving Gateway (SGW), a Policy and Charging Rules Function (PCRF), a Mobility Management Entity (MME) and a wireless device also called a User Equipment (UE). The radio access, E-UTRAN, consists of one or more eNodeBs (eNB).
FIG. 2 shows the overall E-UTRAN architecture and includes eNBs, providing the E-UTRA user plane and control plane protocol terminations towards the UE. The user plane control terminations comprise Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC), and a Physical Layer (PHY). The control plane control terminations comprise Radio Resource Control (RRC) in addition to the listed user plane control terminations. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of the S1 interface to the EPC, more specifically to the MME by means of the S1-MME interface and to the SGW by means of the S1-U interface.
The main parts of the EPC Control Plane and User Plane architectures are shown in FIG. 3 and FIG. 4, respectively.